A Licensed Shared Access (LSA) concept was developed by the Radio Spectrum Policy Group (RSPG) in Europe to address the difficulty of identifying further dedicated frequency spectrum beyond available cellular bands. The LSA concept includes mechanisms for introducing shared spectrum based solutions. These solutions include mobile cellular operators having access to additional licensed spectrum from other primary users (e.g., public safety, government) that they normally would not get access to. The primary uses may be referred to in the art as incumbents.
In Europe, spectrum in a range of 2.3-2.4 GHz is planned to be made available for LSA usage. This spectrum may be referred to in the art as Long-Term Evolution (LTE) Band 40 that is a Time Division Duplex (TDD) band.
The current LSA architecture consists mainly of a unidirectional flow of information from the incumbent (i.e., primary spectrum user) to the cellular operator, via an LSA controller, regarding whether frequency spectrum is available. The current LSA architecture, however, does not include mechanisms for the cellular operator to initiate message exchanges.
There are general needs for improving shared spectrum-based solutions.